How many times inner functions are compiled ?

[Thomas Wouters]

On Tue, Jun 13, 2000 at 02:01:20PM +0200, Jerome Quelin wrote:

> def outer():
>     def inner():
>         print "spam"
>     inner()
> outer()
> outer()

> In the snippet code above, I call outer() two times. I would like to
> know how many times python will compile the inner function ? One time
> when compiling the script/module, or two times, ie at every invocation of the
> outer function ?

Once for every invocation of outer(). Function definitions are to be
considered 'assignment' statements, similar to something like this:

def outer():
  inner = Function("code")

When looking at that bit of code, there is no doubt in your mind that the
creation of the Function object is done once each call, is there ? Nested
functions are not very useful, currently, except to reduce namespace
polution and for simulating closures, like this:

def mk_inner(spam):
	def inner(spam=spam):
		print spam
	return inner

inner = mk_inner(spam)

inner()
inner()
inner()

(Of course, you can do the same by making a class with a __call__ method :)

-- 
Thomas Wouters <thomas at xs4all.net>

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